Economic Burden of Type 2 Diabetes Mellitus in Patients With Cardiovascular Disease in Commercially Insured Patients in the United States

Study conducted by: Wang W, Farrelly EM, Shetty S, et al.

Background

  • Type 2 diabetes mellitus (T2DM) is an important risk factor for cardiovascular disease (CVD) and is associated with a 2- to 4‑fold increase in risk of both CVD and CVD‑related death.1-3
  • However, the extent to which T2DM affects the economic outcomes of patients with CVD is not well documented, hence it is important to quantify the burden of T2DM in this population.

Study Objective

  • To determine the prevalence of T2DM and quantify the healthcare resource utilization (HCRU) and costs associated with T2DM among patients with CVD.

Methods

Data Source and Study Design

  • National commercial claims database (IMS LifeLink PharMetrics Plus)
  • Descriptive, cross-sectional study

Sample/Population Selection

  • Target population: Patients having ≥1 hospitalization claim with diagnosis of a CVD condition in any field, which included myocardial infarction, angina pectoris, heart failure, stroke, other ischemic disease, arrhythmias, cardiac arrest, atherosclerosis, peripheral vascular disease, arterial thrombosis and embolism, cardiomyopathy, conduction disorders, endocarditis, pericarditis, myocarditis, rheumatic heart disease and fever, and other heart disease, or a revascularization procedure; or ≥2 medical claims at least 30 days apart and within 12 months in the outpatient setting with diagnosis of a CVD condition in any field.
  • Inclusion:
    • Patients with CVD conditions during the index year
    • ≥18 years of age as of January 1, 2014
    • Continuous health plan enrollment during the pre-index and index year (January 2013 to December 2014)
  • Exclusion:
    • Diagnosis of pregnancy, gestational diabetes, secondary diabetes, or type 1 diabetes mellitus anytime during the pre‑index or index year
    • Missing demographic information (eg, age, gender, geographic region)
    • Diagnosis of T2DM only in the index year and not the pre‑index year
Study Design

Study Design

Definitions

  • T2DM:
    • ≥1 hospitalization with a diagnosis of T2DM in any diagnosis field OR
    • ≥2 medical claims at least 30 days apart within 12 months in the outpatient setting, except lab and radiology, with a diagnosis of T2DM in any diagnosis field OR
    • ≥1 pharmacy claim indicated for T2DM, including a) a non-insulin injectable, or b) an oral antidiabetic agent, except metformin, or c) metformin pharmacy claim without a diagnosis code for pre‑diabetes or polycystic ovary syndrome4

Study Outcomes

  • Proportion of patients with T2DM: total number of patients identified with T2DM divided by the total study sample with CVD.
  • HCRU
    • All‑cause and CVD‑related (primary diagnosis) length of stay per hospitalization, and bed‑days per patient per year
    • Number of all‑cause and CVD‑related visits by setting of care (reported per patient per year)
  • Healthcare costs (medical and pharmacy) in 2015 United States dollars (USD)
    • Computed using paid amounts on claims
    • All‑cause and CVD‑related costs (reported per patient per year)
  • CVD‑related HCRU and costs were identified as medical claims with a primary diagnosis of a CVD condition, and prescription claims for CVD‑related drugs

Statistical Analysis

  • Sample characteristics and outcomes were compared between study groups using t‑tests for continuous variables and chi-square tests for categorical variables.
  • Statistical analyses were conducted using SAS® version 9.3 (SAS Institute; Cary, NC, USA).
Additional information can be found by downloading the full poster.

References: 1. Centers for Disease Control and Prevention, National Diabetes Statistics Report, 2017. [Accessed: November 20, 2017]. https://www.cdc.gov/diabetes/pdfs/data/statistics/national-diabetes-statistics-report.pdf. 2. Lee WL, Cheung AM, Cape D, Zinman B. Impact of diabetes on coronary artery disease in women and men: a meta‑analysis of prospective studies. Diabetes Care. 2000;23:962‑968. 3. Kannel WB, McGee DL. Diabetes and glucose tolerance as risk factors for cardiovascular disease: the Framingham study. Diabetes Care. 1979;2:120‑126. 4. Solberg LI, Engebretson KI, Sperl‑Hillen JM, et al. Are claims data accurate enough to identify patients for performance measures or quality improvement? The case of diabetes, heart disease, and depression. Am J Med Qual. 2006;21:238‑245.

Sample Characteristics During the Index Year

  • 691,934 CVD patients met the study criteria, 20.3% of whom had T2DM.
  • T2DM group was older, had a higher proportion of males and higher comorbidity burden vs the non‑T2DM group.
  • T2DM group had a higher number of CVD conditions; atherosclerosis/other ischemic heart disease were the most prevalent.
  • Prevalence of revascularization procedures and CVD risk factors were also higher in the T2DM group compared to the non‑T2DM group.

Study Outcomes

  • Among patients with a hospitalization, the average length of stay was significantly longer, and the average number of annual bed‑days was significantly higher, for the T2DM group compared to the non‑T2DM group.
Mean Length of Stay and Bed-days During the Index Year

Mean Length of Stay and Bed‑days During the Index Year

Note: Significant at P<0.01 for all comparisons between groups.
Key: CVD — cardiovascular disease; T2DM — type 2 diabetes mellitus.
  • T2DM group had a significantly higher proportion of patients with all‑cause and CVD‑related HCRU than the non‑T2DM group.
Percentage of Patients with Healthcare Utilization During the Index Year by Setting of Care

Percentage of Patients With Healthcare Utilization During the Index Year by Setting of Care

Note: Significant at P<0.01 for all comparisons between groups.
Key: CVD — cardiovascular disease; T2DM — type 2 diabetes mellitus.
  • All‑cause costs incurred by the T2DM group were higher than those incurred by the non‑T2DM group. Similarly, CVD‑related costs were also higher in the T2DM group compared to the non‑T2DM group.
Mean Healthcare Costs During the Index Year

Mean Healthcare Costs During the Index Year

Note: Significant at P<0.01 for all comparisons between groups.
Key: CVD — cardiovascular disease; T2DM — type 2 diabetes mellitus.
T2DM patients (N=140,155)
Non‑T2DM patients (N=551,779)
Please see the poster for demographic data.

Conclusions

  • Nearly 1 out of every 5 CVD patients had comorbid T2DM.
  • Among patients with CVD, comorbid T2DM was found to be associated with increased all‑cause costs and CVD‑related healthcare resource utilization and costs.
Additional information can be found by downloading the full poster.

Limitations

  • Baseline characteristics between groups were not controlled for, thus confounders like hypertensive disease, rather than CVD, may have contributed to the differences observed in outcomes.
  • Continuous enrollment requirement may have introduced survival bias and did not account for the costs incurred by patients who died.
  • Results of the analysis are primarily generalizable to a commercially insured population
Additional information can be found by downloading the full poster.